Merge branch 'bpf-xdp-sample-libbpf'

Maciej Fijalkowski says:

====================
This patchset tries to address the situation where:
* user loads a particular xdp sample application that does stats polling
* user loads another sample application on the same interface
* then, user sends SIGINT/SIGTERM to the app that was attached as a first one
* second application ends up with an unloaded xdp program

1st patch contains a helper libbpf function for getting the map fd by a
given map name.
In patch 2 Jesper removes the read_trace_pipe usage from xdp_redirect_cpu which
was a blocker for converting this sample to libbpf usage.
3rd patch updates a bunch of xdp samples to make the use of libbpf.
Patch 4 adjusts RLIMIT_MEMLOCK for two samples touched in this patchset.
In patch 5 extack messages are added for cases where dev_change_xdp_fd returns
with an error so user has an idea what was the reason for not attaching the
xdp program onto interface.
Patch 6 makes the samples behavior similar to what iproute2 does when loading
xdp prog - the "force" flag is introduced.
Patch 7 introduces the libbpf function that will query the driver from
userspace about the currently attached xdp prog id.

Use it in samples that do polling by checking the prog id in signal handler
and comparing it with previously stored one which is the scope of patch 8.

Thanks!

v1->v2:
* add a libbpf helper for getting a prog via relative index
* include xdp_redirect_cpu into conversion

v2->v3: mostly addressing Daniel's/Jesper's comments
* get rid of the helper from v1->v2
* feed the xdp_redirect_cpu with program name instead of number

v3->v4:
* fix help message in xdp_sample_pkts

v4->v5:
* in get_link_xdp_fd, assign prog_id only when libbpf_nl_get_link returned
  with 0
* add extack messages in dev_change_xdp_fd
* check the return value of bpf_get_link_xdp_id when exiting from sample progs

v5->v6:
* rebase
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

net/core/dev.c

@@ -7983,8 +7983,10 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 	query = flags & XDP_FLAGS_HW_MODE ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG;
 
 	bpf_op = bpf_chk = ops->ndo_bpf;
-	if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE)))
+	if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) {
+		NL_SET_ERR_MSG(extack, "underlying driver does not support XDP in native mode");
 		return -EOPNOTSUPP;
+	}
 	if (!bpf_op || (flags & XDP_FLAGS_SKB_MODE))
 		bpf_op = generic_xdp_install;
 	if (bpf_op == bpf_chk)
@@ -7992,11 +7994,15 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 
 	if (fd >= 0) {
 		if (__dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG) ||
-		    __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG_HW))
+		    __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG_HW)) {
+			NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
 			return -EEXIST;
+		}
 		if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) &&
-		    __dev_xdp_query(dev, bpf_op, query))
+		    __dev_xdp_query(dev, bpf_op, query)) {
+			NL_SET_ERR_MSG(extack, "XDP program already attached");
 			return -EBUSY;
+		}
 
 		prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
 					     bpf_op == ops->ndo_bpf);

samples/bpf/Makefile

@@ -87,18 +87,18 @@ test_cgrp2_sock2-objs := bpf_load.o test_cgrp2_sock2.o
 xdp1-objs := xdp1_user.o
 # reuse xdp1 source intentionally
 xdp2-objs := xdp1_user.o
-xdp_router_ipv4-objs := bpf_load.o xdp_router_ipv4_user.o
+xdp_router_ipv4-objs := xdp_router_ipv4_user.o
 test_current_task_under_cgroup-objs := bpf_load.o $(CGROUP_HELPERS) \
 				       test_current_task_under_cgroup_user.o
 trace_event-objs := bpf_load.o trace_event_user.o $(TRACE_HELPERS)
 sampleip-objs := bpf_load.o sampleip_user.o $(TRACE_HELPERS)
 tc_l2_redirect-objs := bpf_load.o tc_l2_redirect_user.o
 lwt_len_hist-objs := bpf_load.o lwt_len_hist_user.o
-xdp_tx_iptunnel-objs := bpf_load.o xdp_tx_iptunnel_user.o
+xdp_tx_iptunnel-objs := xdp_tx_iptunnel_user.o
 test_map_in_map-objs := bpf_load.o test_map_in_map_user.o
 per_socket_stats_example-objs := cookie_uid_helper_example.o
-xdp_redirect-objs := bpf_load.o xdp_redirect_user.o
-xdp_redirect_map-objs := bpf_load.o xdp_redirect_map_user.o
+xdp_redirect-objs := xdp_redirect_user.o
+xdp_redirect_map-objs := xdp_redirect_map_user.o
 xdp_redirect_cpu-objs := bpf_load.o xdp_redirect_cpu_user.o
 xdp_monitor-objs := bpf_load.o xdp_monitor_user.o
 xdp_rxq_info-objs := xdp_rxq_info_user.o

samples/bpf/xdp1_user.c

@@ -22,11 +22,23 @@
 #include "bpf/libbpf.h"
 
 static int ifindex;
-static __u32 xdp_flags;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static __u32 prog_id;
 
 static void int_exit(int sig)
 {
-	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(1);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on a given interface\n");
+	else
+		printf("program on interface changed, not removing\n");
 	exit(0);
 }
 
@@ -63,7 +75,8 @@ static void usage(const char *prog)
 		"usage: %s [OPTS] IFACE\n\n"
 		"OPTS:\n"
 		"    -S    use skb-mode\n"
-		"    -N    enforce native mode\n",
+		"    -N    enforce native mode\n"
+		"    -F    force loading prog\n",
 		prog);
 }
 
@@ -73,11 +86,14 @@ int main(int argc, char **argv)
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
-	const char *optstr = "SN";
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	const char *optstr = "FSN";
 	int prog_fd, map_fd, opt;
 	struct bpf_object *obj;
 	struct bpf_map *map;
 	char filename[256];
+	int err;
 
 	while ((opt = getopt(argc, argv, optstr)) != -1) {
 		switch (opt) {
@@ -87,6 +103,9 @@ int main(int argc, char **argv)
 		case 'N':
 			xdp_flags |= XDP_FLAGS_DRV_MODE;
 			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		default:
 			usage(basename(argv[0]));
 			return 1;
@@ -135,6 +154,13 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
+
 	poll_stats(map_fd, 2);
 
 	return 0;

samples/bpf/xdp_adjust_tail_user.c

@@ -24,12 +24,25 @@
 #define STATS_INTERVAL_S 2U
 
 static int ifindex = -1;
-static __u32 xdp_flags;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static __u32 prog_id;
 
 static void int_exit(int sig)
 {
-	if (ifindex > -1)
-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (ifindex > -1) {
+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on a given iface\n");
+		else
+			printf("program on interface changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -60,6 +73,7 @@ static void usage(const char *cmd)
 	printf("    -T <stop-after-X-seconds> Default: 0 (forever)\n");
 	printf("    -S use skb-mode\n");
 	printf("    -N enforce native mode\n");
+	printf("    -F force loading prog\n");
 	printf("    -h Display this help\n");
 }
 
@@ -70,12 +84,15 @@ int main(int argc, char **argv)
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
 	unsigned char opt_flags[256] = {};
+	const char *optstr = "i:T:SNFh";
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	unsigned int kill_after_s = 0;
-	const char *optstr = "i:T:SNh";
 	int i, prog_fd, map_fd, opt;
 	struct bpf_object *obj;
 	struct bpf_map *map;
 	char filename[256];
+	int err;
 
 	for (i = 0; i < strlen(optstr); i++)
 		if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
@@ -96,6 +113,9 @@ int main(int argc, char **argv)
 		case 'N':
 			xdp_flags |= XDP_FLAGS_DRV_MODE;
 			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		default:
 			usage(argv[0]);
 			return 1;
@@ -142,9 +162,15 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
-	poll_stats(map_fd, kill_after_s);
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return 1;
+	}
+	prog_id = info.id;
 
-	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	poll_stats(map_fd, kill_after_s);
+	int_exit(0);
 
 	return 0;
 }

samples/bpf/xdp_redirect_map_user.c

@@ -22,21 +22,48 @@
 #include <libgen.h>
 #include <sys/resource.h>
 
-#include "bpf_load.h"
 #include "bpf_util.h"
 #include <bpf/bpf.h>
+#include "bpf/libbpf.h"
 
 static int ifindex_in;
 static int ifindex_out;
 static bool ifindex_out_xdp_dummy_attached = true;
+static __u32 prog_id;
+static __u32 dummy_prog_id;
 
-static __u32 xdp_flags;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static int rxcnt_map_fd;
 
 static void int_exit(int sig)
 {
-	bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
-	if (ifindex_out_xdp_dummy_attached)
-		bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (bpf_get_link_xdp_id(ifindex_in, &curr_prog_id, xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(1);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on iface IN\n");
+	else
+		printf("program on iface IN changed, not removing\n");
+
+	if (ifindex_out_xdp_dummy_attached) {
+		curr_prog_id = 0;
+		if (bpf_get_link_xdp_id(ifindex_out, &curr_prog_id,
+					xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on iface OUT\n");
+		else
+			printf("program on iface OUT changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -53,7 +80,7 @@ static void poll_stats(int interval, int ifindex)
 		int i;
 
 		sleep(interval);
-		assert(bpf_map_lookup_elem(map_fd[1], &key, values) == 0);
+		assert(bpf_map_lookup_elem(rxcnt_map_fd, &key, values) == 0);
 		for (i = 0; i < nr_cpus; i++)
 			sum += (values[i] - prev[i]);
 		if (sum)
@@ -69,16 +96,26 @@ static void usage(const char *prog)
 		"usage: %s [OPTS] IFINDEX_IN IFINDEX_OUT\n\n"
 		"OPTS:\n"
 		"    -S    use skb-mode\n"
-		"    -N    enforce native mode\n",
+		"    -N    enforce native mode\n"
+		"    -F    force loading prog\n",
 		prog);
 }
 
 int main(int argc, char **argv)
 {
 	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
-	const char *optstr = "SN";
-	char filename[256];
+	struct bpf_prog_load_attr prog_load_attr = {
+		.prog_type	= BPF_PROG_TYPE_XDP,
+	};
+	struct bpf_program *prog, *dummy_prog;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	int prog_fd, dummy_prog_fd;
+	const char *optstr = "FSN";
+	struct bpf_object *obj;
 	int ret, opt, key = 0;
+	char filename[256];
+	int tx_port_map_fd;
 
 	while ((opt = getopt(argc, argv, optstr)) != -1) {
 		switch (opt) {
@@ -88,6 +125,9 @@ int main(int argc, char **argv)
 		case 'N':
 			xdp_flags |= XDP_FLAGS_DRV_MODE;
 			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		default:
 			usage(basename(argv[0]));
 			return 1;
@@ -109,37 +149,65 @@ int main(int argc, char **argv)
 	printf("input: %d output: %d\n", ifindex_in, ifindex_out);
 
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+	prog_load_attr.file = filename;
+
+	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
+		return 1;
 
-	if (load_bpf_file(filename)) {
-		printf("%s", bpf_log_buf);
+	prog = bpf_program__next(NULL, obj);
+	dummy_prog = bpf_program__next(prog, obj);
+	if (!prog || !dummy_prog) {
+		printf("finding a prog in obj file failed\n");
+		return 1;
+	}
+	/* bpf_prog_load_xattr gives us the pointer to first prog's fd,
+	 * so we're missing only the fd for dummy prog
+	 */
+	dummy_prog_fd = bpf_program__fd(dummy_prog);
+	if (prog_fd < 0 || dummy_prog_fd < 0) {
+		printf("bpf_prog_load_xattr: %s\n", strerror(errno));
 		return 1;
 	}
 
-	if (!prog_fd[0]) {
-		printf("load_bpf_file: %s\n", strerror(errno));
+	tx_port_map_fd = bpf_object__find_map_fd_by_name(obj, "tx_port");
+	rxcnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rxcnt");
+	if (tx_port_map_fd < 0 || rxcnt_map_fd < 0) {
+		printf("bpf_object__find_map_fd_by_name failed\n");
 		return 1;
 	}
 
-	if (bpf_set_link_xdp_fd(ifindex_in, prog_fd[0], xdp_flags) < 0) {
+	if (bpf_set_link_xdp_fd(ifindex_in, prog_fd, xdp_flags) < 0) {
 		printf("ERROR: link set xdp fd failed on %d\n", ifindex_in);
 		return 1;
 	}
 
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	prog_id = info.id;
+
 	/* Loading dummy XDP prog on out-device */
-	if (bpf_set_link_xdp_fd(ifindex_out, prog_fd[1],
+	if (bpf_set_link_xdp_fd(ifindex_out, dummy_prog_fd,
 			    (xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {
 		printf("WARN: link set xdp fd failed on %d\n", ifindex_out);
 		ifindex_out_xdp_dummy_attached = false;
 	}
 
+	memset(&info, 0, sizeof(info));
+	ret = bpf_obj_get_info_by_fd(dummy_prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	dummy_prog_id = info.id;
+
 	signal(SIGINT, int_exit);
 	signal(SIGTERM, int_exit);
 
-	printf("map[0] (vports) = %i, map[1] (map) = %i, map[2] (count) = %i\n",
-		map_fd[0], map_fd[1], map_fd[2]);
-
 	/* populate virtual to physical port map */
-	ret = bpf_map_update_elem(map_fd[0], &key, &ifindex_out, 0);
+	ret = bpf_map_update_elem(tx_port_map_fd, &key, &ifindex_out, 0);
 	if (ret) {
 		perror("bpf_update_elem");
 		goto out;

samples/bpf/xdp_redirect_user.c

@@ -22,21 +22,48 @@
 #include <libgen.h>
 #include <sys/resource.h>
 
-#include "bpf_load.h"
 #include "bpf_util.h"
 #include <bpf/bpf.h>
+#include "bpf/libbpf.h"
 
 static int ifindex_in;
 static int ifindex_out;
 static bool ifindex_out_xdp_dummy_attached = true;
+static __u32 prog_id;
+static __u32 dummy_prog_id;
 
-static __u32 xdp_flags;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static int rxcnt_map_fd;
 
 static void int_exit(int sig)
 {
-	bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
-	if (ifindex_out_xdp_dummy_attached)
-		bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (bpf_get_link_xdp_id(ifindex_in, &curr_prog_id, xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(1);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on iface IN\n");
+	else
+		printf("program on iface IN changed, not removing\n");
+
+	if (ifindex_out_xdp_dummy_attached) {
+		curr_prog_id = 0;
+		if (bpf_get_link_xdp_id(ifindex_out, &curr_prog_id,
+					xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on iface OUT\n");
+		else
+			printf("program on iface OUT changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -53,7 +80,7 @@ static void poll_stats(int interval, int ifindex)
 		int i;
 
 		sleep(interval);
-		assert(bpf_map_lookup_elem(map_fd[1], &key, values) == 0);
+		assert(bpf_map_lookup_elem(rxcnt_map_fd, &key, values) == 0);
 		for (i = 0; i < nr_cpus; i++)
 			sum += (values[i] - prev[i]);
 		if (sum)
@@ -69,7 +96,8 @@ static void usage(const char *prog)
 		"usage: %s [OPTS] IFINDEX_IN IFINDEX_OUT\n\n"
 		"OPTS:\n"
 		"    -S    use skb-mode\n"
-		"    -N    enforce native mode\n",
+		"    -N    enforce native mode\n"
+		"    -F    force loading prog\n",
 		prog);
 }
 
@@ -77,9 +105,18 @@ static void usage(const char *prog)
 int main(int argc, char **argv)
 {
 	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
-	const char *optstr = "SN";
+	struct bpf_prog_load_attr prog_load_attr = {
+		.prog_type	= BPF_PROG_TYPE_XDP,
+	};
+	struct bpf_program *prog, *dummy_prog;
+	int prog_fd, tx_port_map_fd, opt;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	const char *optstr = "FSN";
+	struct bpf_object *obj;
 	char filename[256];
-	int ret, opt, key = 0;
+	int dummy_prog_fd;
+	int ret, key = 0;
 
 	while ((opt = getopt(argc, argv, optstr)) != -1) {
 		switch (opt) {
@@ -89,6 +126,9 @@ int main(int argc, char **argv)
 		case 'N':
 			xdp_flags |= XDP_FLAGS_DRV_MODE;
 			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		default:
 			usage(basename(argv[0]));
 			return 1;
@@ -110,34 +150,65 @@ int main(int argc, char **argv)
 	printf("input: %d output: %d\n", ifindex_in, ifindex_out);
 
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+	prog_load_attr.file = filename;
+
+	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
+		return 1;
 
-	if (load_bpf_file(filename)) {
-		printf("%s", bpf_log_buf);
+	prog = bpf_program__next(NULL, obj);
+	dummy_prog = bpf_program__next(prog, obj);
+	if (!prog || !dummy_prog) {
+		printf("finding a prog in obj file failed\n");
+		return 1;
+	}
+	/* bpf_prog_load_xattr gives us the pointer to first prog's fd,
+	 * so we're missing only the fd for dummy prog
+	 */
+	dummy_prog_fd = bpf_program__fd(dummy_prog);
+	if (prog_fd < 0 || dummy_prog_fd < 0) {
+		printf("bpf_prog_load_xattr: %s\n", strerror(errno));
 		return 1;
 	}
 
-	if (!prog_fd[0]) {
-		printf("load_bpf_file: %s\n", strerror(errno));
+	tx_port_map_fd = bpf_object__find_map_fd_by_name(obj, "tx_port");
+	rxcnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rxcnt");
+	if (tx_port_map_fd < 0 || rxcnt_map_fd < 0) {
+		printf("bpf_object__find_map_fd_by_name failed\n");
 		return 1;
 	}
 
-	if (bpf_set_link_xdp_fd(ifindex_in, prog_fd[0], xdp_flags) < 0) {
+	if (bpf_set_link_xdp_fd(ifindex_in, prog_fd, xdp_flags) < 0) {
 		printf("ERROR: link set xdp fd failed on %d\n", ifindex_in);
 		return 1;
 	}
 
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	prog_id = info.id;
+
 	/* Loading dummy XDP prog on out-device */
-	if (bpf_set_link_xdp_fd(ifindex_out, prog_fd[1],
+	if (bpf_set_link_xdp_fd(ifindex_out, dummy_prog_fd,
 			    (xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {
 		printf("WARN: link set xdp fd failed on %d\n", ifindex_out);
 		ifindex_out_xdp_dummy_attached = false;
 	}
 
+	memset(&info, 0, sizeof(info));
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	dummy_prog_id = info.id;
+
 	signal(SIGINT, int_exit);
 	signal(SIGTERM, int_exit);
 
 	/* bpf redirect port */
-	ret = bpf_map_update_elem(map_fd[0], &key, &ifindex_out, 0);
+	ret = bpf_map_update_elem(tx_port_map_fd, &key, &ifindex_out, 0);
 	if (ret) {
 		perror("bpf_update_elem");
 		goto out;

samples/bpf/xdp_router_ipv4_user.c

@@ -15,7 +15,6 @@
 #include <string.h>
 #include <sys/socket.h>
 #include <unistd.h>
-#include "bpf_load.h"
 #include <bpf/bpf.h>
 #include <arpa/inet.h>
 #include <fcntl.h>
@@ -25,32 +24,52 @@
 #include <sys/ioctl.h>
 #include <sys/syscall.h>
 #include "bpf_util.h"
+#include "bpf/libbpf.h"
+#include <sys/resource.h>
+#include <libgen.h>
 
-int sock, sock_arp, flags = 0;
+int sock, sock_arp, flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 static int total_ifindex;
-int *ifindex_list;
+static int *ifindex_list;
+static __u32 *prog_id_list;
 char buf[8192];
+static int lpm_map_fd;
+static int rxcnt_map_fd;
+static int arp_table_map_fd;
+static int exact_match_map_fd;
+static int tx_port_map_fd;
 
 static int get_route_table(int rtm_family);
 static void int_exit(int sig)
 {
+	__u32 prog_id = 0;
 	int i = 0;
 
-	for (i = 0; i < total_ifindex; i++)
-		bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
+	for (i = 0; i < total_ifindex; i++) {
+		if (bpf_get_link_xdp_id(ifindex_list[i], &prog_id, flags)) {
+			printf("bpf_get_link_xdp_id on iface %d failed\n",
+			       ifindex_list[i]);
+			exit(1);
+		}
+		if (prog_id_list[i] == prog_id)
+			bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
+		else if (!prog_id)
+			printf("couldn't find a prog id on iface %d\n",
+			       ifindex_list[i]);
+		else
+			printf("program on iface %d changed, not removing\n",
+			       ifindex_list[i]);
+		prog_id = 0;
+	}
 	exit(0);
 }
 
 static void close_and_exit(int sig)
 {
-	int i = 0;
-
 	close(sock);
 	close(sock_arp);
 
-	for (i = 0; i < total_ifindex; i++)
-		bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
-	exit(0);
+	int_exit(0);
 }
 
 /* Get the mac address of the interface given interface name */
@@ -179,14 +198,10 @@ static void read_route(struct nlmsghdr *nh, int nll)
 		route.iface_name = alloca(sizeof(char *) * IFNAMSIZ);
 		route.iface_name = if_indextoname(route.iface, route.iface_name);
 		route.mac = getmac(route.iface_name);
-		if (route.mac == -1) {
-			int i = 0;
-
-			for (i = 0; i < total_ifindex; i++)
-				bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
-			exit(0);
-		}
-		assert(bpf_map_update_elem(map_fd[4], &route.iface, &route.iface, 0) == 0);
+		if (route.mac == -1)
+			int_exit(0);
+		assert(bpf_map_update_elem(tx_port_map_fd,
+					   &route.iface, &route.iface, 0) == 0);
 		if (rtm_family == AF_INET) {
 			struct trie_value {
 				__u8 prefix[4];
@@ -207,11 +222,16 @@ static void read_route(struct nlmsghdr *nh, int nll)
 			direct_entry.arp.dst = 0;
 			if (route.dst_len == 32) {
 				if (nh->nlmsg_type == RTM_DELROUTE) {
-					assert(bpf_map_delete_elem(map_fd[3], &route.dst) == 0);
+					assert(bpf_map_delete_elem(exact_match_map_fd,
+								   &route.dst) == 0);
 				} else {
-					if (bpf_map_lookup_elem(map_fd[2], &route.dst, &direct_entry.arp.mac) == 0)
+					if (bpf_map_lookup_elem(arp_table_map_fd,
+								&route.dst,
+								&direct_entry.arp.mac) == 0)
 						direct_entry.arp.dst = route.dst;
-					assert(bpf_map_update_elem(map_fd[3], &route.dst, &direct_entry, 0) == 0);
+					assert(bpf_map_update_elem(exact_match_map_fd,
+								   &route.dst,
+								   &direct_entry, 0) == 0);
 				}
 			}
 			for (i = 0; i < 4; i++)
@@ -225,7 +245,7 @@ static void read_route(struct nlmsghdr *nh, int nll)
 			       route.gw, route.dst_len,
 			       route.metric,
 			       route.iface_name);
-			if (bpf_map_lookup_elem(map_fd[0], prefix_key,
+			if (bpf_map_lookup_elem(lpm_map_fd, prefix_key,
 						prefix_value) < 0) {
 				for (i = 0; i < 4; i++)
 					prefix_value->prefix[i] = prefix_key->data[i];
@@ -234,7 +254,7 @@ static void read_route(struct nlmsghdr *nh, int nll)
 				prefix_value->gw = route.gw;
 				prefix_value->metric = route.metric;
 
-				assert(bpf_map_update_elem(map_fd[0],
+				assert(bpf_map_update_elem(lpm_map_fd,
 							   prefix_key,
 							   prefix_value, 0
 							   ) == 0);
@@ -247,7 +267,7 @@ static void read_route(struct nlmsghdr *nh, int nll)
 					       prefix_key->data[2],
 					       prefix_key->data[3],
 					       prefix_key->prefixlen);
-					assert(bpf_map_delete_elem(map_fd[0],
+					assert(bpf_map_delete_elem(lpm_map_fd,
 								   prefix_key
 								   ) == 0);
 					/* Rereading the route table to check if
@@ -275,8 +295,7 @@ static void read_route(struct nlmsghdr *nh, int nll)
 					prefix_value->ifindex = route.iface;
 					prefix_value->gw = route.gw;
 					prefix_value->metric = route.metric;
-					assert(bpf_map_update_elem(
-								   map_fd[0],
+					assert(bpf_map_update_elem(lpm_map_fd,
 								   prefix_key,
 								   prefix_value,
 								   0) == 0);
@@ -401,7 +420,8 @@ static void read_arp(struct nlmsghdr *nh, int nll)
 		arp_entry.mac = atol(mac);
 		printf("%x\t\t%llx\n", arp_entry.dst, arp_entry.mac);
 		if (ndm_family == AF_INET) {
-			if (bpf_map_lookup_elem(map_fd[3], &arp_entry.dst,
+			if (bpf_map_lookup_elem(exact_match_map_fd,
+						&arp_entry.dst,
 						&direct_entry) == 0) {
 				if (nh->nlmsg_type == RTM_DELNEIGH) {
 					direct_entry.arp.dst = 0;
@@ -410,16 +430,17 @@ static void read_arp(struct nlmsghdr *nh, int nll)
 					direct_entry.arp.dst = arp_entry.dst;
 					direct_entry.arp.mac = arp_entry.mac;
 				}
-				assert(bpf_map_update_elem(map_fd[3],
+				assert(bpf_map_update_elem(exact_match_map_fd,
 							   &arp_entry.dst,
 							   &direct_entry, 0
 							   ) == 0);
 				memset(&direct_entry, 0, sizeof(direct_entry));
 			}
 			if (nh->nlmsg_type == RTM_DELNEIGH) {
-				assert(bpf_map_delete_elem(map_fd[2], &arp_entry.dst) == 0);
+				assert(bpf_map_delete_elem(arp_table_map_fd,
+							   &arp_entry.dst) == 0);
 			} else if (nh->nlmsg_type == RTM_NEWNEIGH) {
-				assert(bpf_map_update_elem(map_fd[2],
+				assert(bpf_map_update_elem(arp_table_map_fd,
 							   &arp_entry.dst,
 							   &arp_entry.mac, 0
 							   ) == 0);
@@ -553,7 +574,8 @@ static int monitor_route(void)
 		for (key = 0; key < nr_keys; key++) {
 			__u64 sum = 0;
 
-			assert(bpf_map_lookup_elem(map_fd[1], &key, values) == 0);
+			assert(bpf_map_lookup_elem(rxcnt_map_fd,
+						   &key, values) == 0);
 			for (i = 0; i < nr_cpus; i++)
 				sum += (values[i] - prev[key][i]);
 			if (sum)
@@ -594,36 +616,87 @@ static int monitor_route(void)
 	return ret;
 }
 
+static void usage(const char *prog)
+{
+	fprintf(stderr,
+		"%s: %s [OPTS] interface name list\n\n"
+		"OPTS:\n"
+		"    -S    use skb-mode\n"
+		"    -F    force loading prog\n",
+		__func__, prog);
+}
+
 int main(int ac, char **argv)
 {
+	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+	struct bpf_prog_load_attr prog_load_attr = {
+		.prog_type	= BPF_PROG_TYPE_XDP,
+	};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	const char *optstr = "SF";
+	struct bpf_object *obj;
 	char filename[256];
 	char **ifname_list;
-	int i = 1;
+	int prog_fd, opt;
+	int err, i = 1;
 
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
-	if (ac < 2) {
-		printf("usage: %s [-S] Interface name list\n", argv[0]);
-		return 1;
+	prog_load_attr.file = filename;
+
+	total_ifindex = ac - 1;
+	ifname_list = (argv + 1);
+
+	while ((opt = getopt(ac, argv, optstr)) != -1) {
+		switch (opt) {
+		case 'S':
+			flags |= XDP_FLAGS_SKB_MODE;
+			total_ifindex--;
+			ifname_list++;
+			break;
+		case 'F':
+			flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			total_ifindex--;
+			ifname_list++;
+			break;
+		default:
+			usage(basename(argv[0]));
+			return 1;
+		}
 	}
-	if (!strcmp(argv[1], "-S")) {
-		flags = XDP_FLAGS_SKB_MODE;
-		total_ifindex = ac - 2;
-		ifname_list = (argv + 2);
-	} else {
-		flags = 0;
-		total_ifindex = ac - 1;
-		ifname_list = (argv + 1);
+
+	if (optind == ac) {
+		usage(basename(argv[0]));
+		return 1;
 	}
-	if (load_bpf_file(filename)) {
-		printf("%s", bpf_log_buf);
+
+	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+		perror("setrlimit(RLIMIT_MEMLOCK)");
 		return 1;
 	}
+
+	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
+		return 1;
+
 	printf("\n**************loading bpf file*********************\n\n\n");
-	if (!prog_fd[0]) {
-		printf("load_bpf_file: %s\n", strerror(errno));
+	if (!prog_fd) {
+		printf("bpf_prog_load_xattr: %s\n", strerror(errno));
 		return 1;
 	}
-	ifindex_list = (int *)malloc(total_ifindex * sizeof(int *));
+
+	lpm_map_fd = bpf_object__find_map_fd_by_name(obj, "lpm_map");
+	rxcnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rxcnt");
+	arp_table_map_fd = bpf_object__find_map_fd_by_name(obj, "arp_table");
+	exact_match_map_fd = bpf_object__find_map_fd_by_name(obj,
+							     "exact_match");
+	tx_port_map_fd = bpf_object__find_map_fd_by_name(obj, "tx_port");
+	if (lpm_map_fd < 0 || rxcnt_map_fd < 0 || arp_table_map_fd < 0 ||
+	    exact_match_map_fd < 0 || tx_port_map_fd < 0) {
+		printf("bpf_object__find_map_fd_by_name failed\n");
+		return 1;
+	}
+
+	ifindex_list = (int *)calloc(total_ifindex, sizeof(int *));
 	for (i = 0; i < total_ifindex; i++) {
 		ifindex_list[i] = if_nametoindex(ifname_list[i]);
 		if (!ifindex_list[i]) {
@@ -632,8 +705,9 @@ int main(int ac, char **argv)
 			return 1;
 		}
 	}
+	prog_id_list = (__u32 *)calloc(total_ifindex, sizeof(__u32 *));
 	for (i = 0; i < total_ifindex; i++) {
-		if (bpf_set_link_xdp_fd(ifindex_list[i], prog_fd[0], flags) < 0) {
+		if (bpf_set_link_xdp_fd(ifindex_list[i], prog_fd, flags) < 0) {
 			printf("link set xdp fd failed\n");
 			int recovery_index = i;
 
@@ -642,6 +716,13 @@ int main(int ac, char **argv)
 
 			return 1;
 		}
+		err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+		if (err) {
+			printf("can't get prog info - %s\n", strerror(errno));
+			return err;
+		}
+		prog_id_list[i] = info.id;
+		memset(&info, 0, sizeof(info));
 		printf("Attached to %d\n", ifindex_list[i]);
 	}
 	signal(SIGINT, int_exit);

samples/bpf/xdp_rxq_info_user.c

@@ -29,8 +29,9 @@ static const char *__doc__ = " XDP RX-queue info extract example\n\n"
 static int ifindex = -1;
 static char ifname_buf[IF_NAMESIZE];
 static char *ifname;
+static __u32 prog_id;
 
-static __u32 xdp_flags;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 
 static struct bpf_map *stats_global_map;
 static struct bpf_map *rx_queue_index_map;
@@ -52,16 +53,30 @@ static const struct option long_options[] = {
 	{"action",	required_argument,	NULL, 'a' },
 	{"readmem", 	no_argument,		NULL, 'r' },
 	{"swapmac", 	no_argument,		NULL, 'm' },
+	{"force",	no_argument,		NULL, 'F' },
 	{0, 0, NULL,  0 }
 };
 
 static void int_exit(int sig)
 {
-	fprintf(stderr,
-		"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
-		ifindex, ifname);
-	if (ifindex > -1)
-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (ifindex > -1) {
+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(EXIT_FAIL);
+		}
+		if (prog_id == curr_prog_id) {
+			fprintf(stderr,
+				"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
+				ifindex, ifname);
+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+		} else if (!curr_prog_id) {
+			printf("couldn't find a prog id on a given iface\n");
+		} else {
+			printf("program on interface changed, not removing\n");
+		}
+	}
 	exit(EXIT_OK);
 }
 
@@ -446,6 +461,8 @@ int main(int argc, char **argv)
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	int prog_fd, map_fd, opt, err;
 	bool use_separators = true;
 	struct config cfg = { 0 };
@@ -487,7 +504,7 @@ int main(int argc, char **argv)
 	}
 
 	/* Parse commands line args */
-	while ((opt = getopt_long(argc, argv, "hSd:",
+	while ((opt = getopt_long(argc, argv, "FhSrmzd:s:a:",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
 		case 'd':
@@ -524,6 +541,9 @@ int main(int argc, char **argv)
 		case 'm':
 			cfg_options |= SWAP_MAC;
 			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		case 'h':
 		error:
 		default:
@@ -576,6 +596,13 @@ int main(int argc, char **argv)
 		return EXIT_FAIL_XDP;
 	}
 
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
+
 	stats_poll(interval, action, cfg_options);
 	return EXIT_OK;
 }

samples/bpf/xdp_sample_pkts_user.c

@@ -12,6 +12,9 @@
 #include <signal.h>
 #include <libbpf.h>
 #include <bpf/bpf.h>
+#include <sys/resource.h>
+#include <libgen.h>
+#include <linux/if_link.h>
 
 #include "perf-sys.h"
 #include "trace_helpers.h"
@@ -20,25 +23,50 @@
 static int pmu_fds[MAX_CPUS], if_idx;
 static struct perf_event_mmap_page *headers[MAX_CPUS];
 static char *if_name;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static __u32 prog_id;
 
 static int do_attach(int idx, int fd, const char *name)
 {
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	int err;
 
-	err = bpf_set_link_xdp_fd(idx, fd, 0);
-	if (err < 0)
+	err = bpf_set_link_xdp_fd(idx, fd, xdp_flags);
+	if (err < 0) {
 		printf("ERROR: failed to attach program to %s\n", name);
+		return err;
+	}
+
+	err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
 
 	return err;
 }
 
 static int do_detach(int idx, const char *name)
 {
-	int err;
+	__u32 curr_prog_id = 0;
+	int err = 0;
 
-	err = bpf_set_link_xdp_fd(idx, -1, 0);
-	if (err < 0)
-		printf("ERROR: failed to detach program from %s\n", name);
+	err = bpf_get_link_xdp_id(idx, &curr_prog_id, 0);
+	if (err) {
+		printf("bpf_get_link_xdp_id failed\n");
+		return err;
+	}
+	if (prog_id == curr_prog_id) {
+		err = bpf_set_link_xdp_fd(idx, -1, 0);
+		if (err < 0)
+			printf("ERROR: failed to detach prog from %s\n", name);
+	} else if (!curr_prog_id) {
+		printf("couldn't find a prog id on a %s\n", name);
+	} else {
+		printf("program on interface changed, not removing\n");
+	}
 
 	return err;
 }
@@ -97,20 +125,47 @@ static void sig_handler(int signo)
 	exit(0);
 }
 
+static void usage(const char *prog)
+{
+	fprintf(stderr,
+		"%s: %s [OPTS] <ifname|ifindex>\n\n"
+		"OPTS:\n"
+		"    -F    force loading prog\n",
+		__func__, prog);
+}
+
 int main(int argc, char **argv)
 {
+	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
+	const char *optstr = "F";
+	int prog_fd, map_fd, opt;
 	struct bpf_object *obj;
 	struct bpf_map *map;
-	int prog_fd, map_fd;
 	char filename[256];
 	int ret, err, i;
 	int numcpus;
 
-	if (argc < 2) {
-		printf("Usage: %s <ifname>\n", argv[0]);
+	while ((opt = getopt(argc, argv, optstr)) != -1) {
+		switch (opt) {
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
+		default:
+			usage(basename(argv[0]));
+			return 1;
+		}
+	}
+
+	if (optind == argc) {
+		usage(basename(argv[0]));
+		return 1;
+	}
+
+	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+		perror("setrlimit(RLIMIT_MEMLOCK)");
 		return 1;
 	}
 
@@ -136,16 +191,16 @@ int main(int argc, char **argv)
 	}
 	map_fd = bpf_map__fd(map);
 
-	if_idx = if_nametoindex(argv[1]);
+	if_idx = if_nametoindex(argv[optind]);
 	if (!if_idx)
-		if_idx = strtoul(argv[1], NULL, 0);
+		if_idx = strtoul(argv[optind], NULL, 0);
 
 	if (!if_idx) {
 		fprintf(stderr, "Invalid ifname\n");
 		return 1;
 	}
-	if_name = argv[1];
-	err = do_attach(if_idx, prog_fd, argv[1]);
+	if_name = argv[optind];
+	err = do_attach(if_idx, prog_fd, if_name);
 	if (err)
 		return err;
 

samples/bpf/xdp_tx_iptunnel_user.c

@@ -17,7 +17,7 @@
 #include <netinet/ether.h>
 #include <unistd.h>
 #include <time.h>
-#include "bpf_load.h"
+#include "bpf/libbpf.h"
 #include <bpf/bpf.h>
 #include "bpf_util.h"
 #include "xdp_tx_iptunnel_common.h"
@@ -25,12 +25,26 @@
 #define STATS_INTERVAL_S 2U
 
 static int ifindex = -1;
-static __u32 xdp_flags = 0;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static int rxcnt_map_fd;
+static __u32 prog_id;
 
 static void int_exit(int sig)
 {
-	if (ifindex > -1)
-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (ifindex > -1) {
+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on a given iface\n");
+		else
+			printf("program on interface changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -53,7 +67,8 @@ static void poll_stats(unsigned int kill_after_s)
 		for (proto = 0; proto < nr_protos; proto++) {
 			__u64 sum = 0;
 
-			assert(bpf_map_lookup_elem(map_fd[0], &proto, values) == 0);
+			assert(bpf_map_lookup_elem(rxcnt_map_fd, &proto,
+						   values) == 0);
 			for (i = 0; i < nr_cpus; i++)
 				sum += (values[i] - prev[proto][i]);
 
@@ -81,6 +96,7 @@ static void usage(const char *cmd)
 	printf("    -P <IP-Protocol> Default is TCP\n");
 	printf("    -S use skb-mode\n");
 	printf("    -N enforce native mode\n");
+	printf("    -F Force loading the XDP prog\n");
 	printf("    -h Display this help\n");
 }
 
@@ -138,16 +154,22 @@ static int parse_ports(const char *port_str, int *min_port, int *max_port)
 
 int main(int argc, char **argv)
 {
+	struct bpf_prog_load_attr prog_load_attr = {
+		.prog_type	= BPF_PROG_TYPE_XDP,
+	};
+	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+	int min_port = 0, max_port = 0, vip2tnl_map_fd;
+	const char *optstr = "i:a:p:s:d:m:T:P:FSNh";
 	unsigned char opt_flags[256] = {};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	unsigned int kill_after_s = 0;
-	const char *optstr = "i:a:p:s:d:m:T:P:SNh";
-	int min_port = 0, max_port = 0;
 	struct iptnl_info tnl = {};
-	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
+	struct bpf_object *obj;
 	struct vip vip = {};
 	char filename[256];
-	int opt;
-	int i;
+	int opt, prog_fd;
+	int i, err;
 
 	tnl.family = AF_UNSPEC;
 	vip.protocol = IPPROTO_TCP;
@@ -211,6 +233,9 @@ int main(int argc, char **argv)
 		case 'N':
 			xdp_flags |= XDP_FLAGS_DRV_MODE;
 			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		default:
 			usage(argv[0]);
 			return 1;
@@ -232,33 +257,47 @@ int main(int argc, char **argv)
 	}
 
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+	prog_load_attr.file = filename;
 
-	if (load_bpf_file(filename)) {
-		printf("%s", bpf_log_buf);
+	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
 		return 1;
-	}
 
-	if (!prog_fd[0]) {
+	if (!prog_fd) {
 		printf("load_bpf_file: %s\n", strerror(errno));
 		return 1;
 	}
 
+	rxcnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rxcnt");
+	vip2tnl_map_fd = bpf_object__find_map_fd_by_name(obj, "vip2tnl");
+	if (vip2tnl_map_fd < 0 || rxcnt_map_fd < 0) {
+		printf("bpf_object__find_map_fd_by_name failed\n");
+		return 1;
+	}
+
 	signal(SIGINT, int_exit);
 	signal(SIGTERM, int_exit);
 
 	while (min_port <= max_port) {
 		vip.dport = htons(min_port++);
-		if (bpf_map_update_elem(map_fd[1], &vip, &tnl, BPF_NOEXIST)) {
+		if (bpf_map_update_elem(vip2tnl_map_fd, &vip, &tnl,
+					BPF_NOEXIST)) {
 			perror("bpf_map_update_elem(&vip2tnl)");
 			return 1;
 		}
 	}
 
-	if (bpf_set_link_xdp_fd(ifindex, prog_fd[0], xdp_flags) < 0) {
+	if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {
 		printf("link set xdp fd failed\n");
 		return 1;
 	}
 
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
+
 	poll_stats(kill_after_s);
 
 	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);

samples/bpf/xdpsock_user.c

@@ -68,7 +68,7 @@ enum benchmark_type {
 };
 
 static enum benchmark_type opt_bench = BENCH_RXDROP;
-static u32 opt_xdp_flags;
+static u32 opt_xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 static const char *opt_if = "";
 static int opt_ifindex;
 static int opt_queue;
@@ -76,6 +76,7 @@ static int opt_poll;
 static int opt_shared_packet_buffer;
 static int opt_interval = 1;
 static u32 opt_xdp_bind_flags;
+static __u32 prog_id;
 
 struct xdp_umem_uqueue {
 	u32 cached_prod;
@@ -631,9 +632,20 @@ static void *poller(void *arg)
 
 static void int_exit(int sig)
 {
+	__u32 curr_prog_id = 0;
+
 	(void)sig;
 	dump_stats();
-	bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags);
+	if (bpf_get_link_xdp_id(opt_ifindex, &curr_prog_id, opt_xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(EXIT_FAILURE);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on a given interface\n");
+	else
+		printf("program on interface changed, not removing\n");
 	exit(EXIT_SUCCESS);
 }
 
@@ -682,7 +694,7 @@ static void parse_command_line(int argc, char **argv)
 	opterr = 0;
 
 	for (;;) {
-		c = getopt_long(argc, argv, "rtli:q:psSNn:cz", long_options,
+		c = getopt_long(argc, argv, "Frtli:q:psSNn:cz", long_options,
 				&option_index);
 		if (c == -1)
 			break;
@@ -725,6 +737,9 @@ static void parse_command_line(int argc, char **argv)
 		case 'c':
 			opt_xdp_bind_flags |= XDP_COPY;
 			break;
+		case 'F':
+			opt_xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		default:
 			usage(basename(argv[0]));
 		}
@@ -904,6 +919,8 @@ int main(int argc, char **argv)
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
 	int prog_fd, qidconf_map, xsks_map;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	struct bpf_object *obj;
 	char xdp_filename[256];
 	struct bpf_map *map;
@@ -950,6 +967,13 @@ int main(int argc, char **argv)
 		exit(EXIT_FAILURE);
 	}
 
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return 1;
+	}
+	prog_id = info.id;
+
 	ret = bpf_map_update_elem(qidconf_map, &key, &opt_queue, 0);
 	if (ret) {
 		fprintf(stderr, "ERROR: bpf_map_update_elem qidconf\n");

tools/lib/bpf/libbpf.c

@@ -2884,6 +2884,12 @@ bpf_object__find_map_by_name(struct bpf_object *obj, const char *name)
 	return NULL;
 }
 
+int
+bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name)
+{
+	return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
+}
+
 struct bpf_map *
 bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset)
 {

tools/lib/bpf/libbpf.h

@@ -264,6 +264,9 @@ struct bpf_map;
 LIBBPF_API struct bpf_map *
 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name);
 
+LIBBPF_API int
+bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name);
+
 /*
  * Get bpf_map through the offset of corresponding struct bpf_map_def
  * in the BPF object file.
@@ -314,6 +317,7 @@ LIBBPF_API int bpf_prog_load(const char *file, enum bpf_prog_type type,
 			     struct bpf_object **pobj, int *prog_fd);
 
 LIBBPF_API int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);
+LIBBPF_API int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags);
 
 enum bpf_perf_event_ret {
 	LIBBPF_PERF_EVENT_DONE	= 0,

tools/lib/bpf/libbpf.map

@@ -131,4 +131,6 @@ LIBBPF_0.0.2 {
 		bpf_probe_map_type;
 		bpf_probe_prog_type;
 		bpf_map_lookup_elem_flags;
+		bpf_object__find_map_fd_by_name;
+		bpf_get_link_xdp_id;
 } LIBBPF_0.0.1;

tools/lib/bpf/netlink.c

@@ -21,6 +21,12 @@
 typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, libbpf_dump_nlmsg_t,
 			      void *cookie);
 
+struct xdp_id_md {
+	int ifindex;
+	__u32 flags;
+	__u32 id;
+};
+
 int libbpf_netlink_open(__u32 *nl_pid)
 {
 	struct sockaddr_nl sa;
@@ -196,6 +202,85 @@ static int __dump_link_nlmsg(struct nlmsghdr *nlh,
 	return dump_link_nlmsg(cookie, ifi, tb);
 }
 
+static unsigned char get_xdp_id_attr(unsigned char mode, __u32 flags)
+{
+	if (mode != XDP_ATTACHED_MULTI)
+		return IFLA_XDP_PROG_ID;
+	if (flags & XDP_FLAGS_DRV_MODE)
+		return IFLA_XDP_DRV_PROG_ID;
+	if (flags & XDP_FLAGS_HW_MODE)
+		return IFLA_XDP_HW_PROG_ID;
+	if (flags & XDP_FLAGS_SKB_MODE)
+		return IFLA_XDP_SKB_PROG_ID;
+
+	return IFLA_XDP_UNSPEC;
+}
+
+static int get_xdp_id(void *cookie, void *msg, struct nlattr **tb)
+{
+	struct nlattr *xdp_tb[IFLA_XDP_MAX + 1];
+	struct xdp_id_md *xdp_id = cookie;
+	struct ifinfomsg *ifinfo = msg;
+	unsigned char mode, xdp_attr;
+	int ret;
+
+	if (xdp_id->ifindex && xdp_id->ifindex != ifinfo->ifi_index)
+		return 0;
+
+	if (!tb[IFLA_XDP])
+		return 0;
+
+	ret = libbpf_nla_parse_nested(xdp_tb, IFLA_XDP_MAX, tb[IFLA_XDP], NULL);
+	if (ret)
+		return ret;
+
+	if (!xdp_tb[IFLA_XDP_ATTACHED])
+		return 0;
+
+	mode = libbpf_nla_getattr_u8(xdp_tb[IFLA_XDP_ATTACHED]);
+	if (mode == XDP_ATTACHED_NONE)
+		return 0;
+
+	xdp_attr = get_xdp_id_attr(mode, xdp_id->flags);
+	if (!xdp_attr || !xdp_tb[xdp_attr])
+		return 0;
+
+	xdp_id->id = libbpf_nla_getattr_u32(xdp_tb[xdp_attr]);
+
+	return 0;
+}
+
+int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags)
+{
+	struct xdp_id_md xdp_id = {};
+	int sock, ret;
+	__u32 nl_pid;
+	__u32 mask;
+
+	if (flags & ~XDP_FLAGS_MASK)
+		return -EINVAL;
+
+	/* Check whether the single {HW,DRV,SKB} mode is set */
+	flags &= (XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE);
+	mask = flags - 1;
+	if (flags && flags & mask)
+		return -EINVAL;
+
+	sock = libbpf_netlink_open(&nl_pid);
+	if (sock < 0)
+		return sock;
+
+	xdp_id.ifindex = ifindex;
+	xdp_id.flags = flags;
+
+	ret = libbpf_nl_get_link(sock, nl_pid, get_xdp_id, &xdp_id);
+	if (!ret)
+		*prog_id = xdp_id.id;
+
+	close(sock);
+	return ret;
+}
+
 int libbpf_nl_get_link(int sock, unsigned int nl_pid,
 		       libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
 {